U.S. President Barack Obama said on Sunday that nothing had been “given away” to Iran during weekend nuclear talks in Istanbul, AFP reported.

According to the report, Obama warned Tehran that the clock was still ticking to reach an agreement over its nuclear program.

Obama’s comments came in response to comments made by Israeli Prime Minister Binyamin Netanyahu, who said during a meeting with U.S. Senator Joe Lieberman, “My initial impression is that Iran has been given a freebie. It’s got five weeks to continue enrichment without any limitation.”

On Saturday, the European Union’s foreign policy chief, Catherine Ashton, said the talks have been constructive and that the sides will meet again in Baghdad on May 23.

Obama rejected the idea that Iran has been given a ‘freebie’ and was quoted by AFP as having said, “The clock is ticking and I’ve been very clear to Iran and our negotiating partners that we’re not going to have these talks just drag out in a stalling process.”

Obama, who spoke to reporters after an Americas summit in Colombia, added, “But so far at least we haven’t given away anything — other than the opportunity for us to negotiate.”

He refuted Netanyahu’s statement, saying, “The notion that we’ve given something away or a freebie would indicate that Iran has gotten something.”

“In fact, they got the toughest sanctions that they’re going to be facing coming up in a few months if they don’t take advantage of those talks. I hope they do,” Obama said.

The UN Security Council has slapped four rounds of sanctions on Tehran over suspicions that Iran is seeking a militarized nuclear capability. Tehran has denied the charges.